Short answers, pulled from the story.
A tundra is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. Tundra vegetation consists of dwarf shrubs, sedges, grasses, mosses, and lichens instead of trees.
The first use of tundra in English occurred in 1824 with the spelling toundra. This usage possibly indicates borrowing from French or the Sámi language family dating back to the 16th century.
Arctic tundra occurs in the far Northern Hemisphere north of the taiga belt including vast areas of northern Russia and Canada. The polar tundra is home to several peoples who are mostly nomadic reindeer herders such as the Nganasan and Nenets.
Antarctic tundra flora presently consists of around 300 to 400 species of lichens plus 100 mosses and 25 liverworts. There are also around 700 terrestrial and aquatic algae species living on exposed rock and soil around the shore of the continent.
Climate change causes permafrost to thaw which releases stored methane and carbon dioxide into the atmosphere. This creates a feedback cycle that contributes to global warming while potentially releasing up to 150 billion tons of carbon dioxide equivalent per degree Celsius of warming.